The efforts detailed within are steps in the overall goal of utilizing intracellular indicators of oxidative metabolic activity to assess the changes that occur during cerebral anoxia/ischemia and to determine the factors most critical to overall tissue viability during and following periods of circulatory compromise. Non-invasive techniques of fluorometrically monitoring changes in the reduction/oxidation ration of intramitochondrial NAD and the technique of reflection spectrophotometry to measure redox changes of cytochromes together with changes in hemoglobin oxygenation and local blood volume will be utilized. By relating parameters of metabolism and function, we will discern how vulnerability of functional activity is associated with periods of ischemic insult. We will continue efforts to define the relationships between energy metabolism and the functioning of the central nervous system to increase our understanding of how and why the brain uses oxygen, metabolic substrates and oxidative energy and to determine how viability is threatened by the loss of oxygen and circulatory perfusion.